Accession Number : ADA332571

Title :   Stability and Thermal Influences in Continuum Mechanics and Materials Science

Descriptive Note : Final progress rept

Corporate Author : CARNEGIE-MELLON UNIV PITTSBURGH PA

Personal Author(s) : Gurtin, Morton E.

PDF Url : ADA332571

Report Date : 25 AUG 1997

Pagination or Media Count : 6

Abstract : Work continued on order parameter theories of two-phase continua. This work differs from past work in the introduction a balance law for microforces associated with the kinematics of the order parameter and the use of the second-law to develop constitutive equations. A general framework for dynamical fracture is developed based on the notion of configurational forces in conjunction with a mechanical version of the second law. Here, as with other work done on this project, configurational forces are viewed as basic objects consistent with their own force balance. This balance yields a kinetic relation for the evolution of straight cracks. Kinking and curving of cracks is based on the requirement that the crack propagate in the direction that maximizes the energy dissipatation. Explicit relations for the initial kink angle and the subsequent direction of propagation are given. A continuum framework is developed for recrystallization. The driving force is the energy stored in dislocation substructures, characterized with the aid of a scalar measure, the dislocation content. A relation is obtained characterizing the efficiency with which dislocation substructure is eliminated by moving grain boundaries.

Descriptors :   *PHASE TRANSFORMATIONS, *CONTINUUM MECHANICS, DEFORMATION, SOLIDS, SHOCK, IMPACT LOADS.

Subject Categories : Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE